In general, according to the combustion scheme of an internal combustion engine, gaseous or liquefied hydrocarbon fuel is atomized by forcibly spraying the gaseous or liquefied hydrocarbon fuel into a combustion chamber of the internal combustion engine through a spray nozzle. However, the above combustion scheme has problems in that the combustion efficiency is insufficient and pollutants generated due to the incomplete combustion and contained in exhaust gas are exhausted to the atmosphere, thereby causing the air pollution.
In order to solve the above problems, many studies have been pursued to promote the combustion of fuel supplied to the internal combustion engine. One of them is to appropriately apply heat to the fuel supplied to the internal combustion engine such that the fuel can be evaporated due to the heat when the fuel is sprayed into the combustion chamber. According to the above scheme, the combustion can be promoted, the fuel supply can be reduced and the reaction with oxygen can be promoted by increasing pressure in a cylinder. However, according to the above scheme, a vehicle must be equipped with a device for applying heat to the fuel introduced into the internal combustion engine and must provide power consumed to supply the heat, so great energy consumption may be caused. In particular, the apparatus may have the complicate structure, so the installation work thereof is very difficult and the fuel consumption reduction and smoke reduction effects may be insufficient.